escape bugs

Concept

Escape bugs are defects in microprocessor designs that are not detected during the pre-silicon functional verification process and therefore 'escape' into manufactured hardware. In the microprocessor design verification literature, they are treated as a primary motivation for adopting rigorous, plan-driven verification methodologies, with the 1994 Pentium floating-point defects cited as a canonical example.

First seen 6/9/2026

Last seen 6/19/2026

Evidence 5 chunks

Wiki v1

WIKI

Definition

In the context of microprocessor functional verification, an escape bug is a design defect that is not detected by the verification effort prior to tape-out or release, and therefore propagates into the manufactured silicon where it can be observed by end users. The term emphasizes the failure mode of the verification process: the bug is not merely present in the design, but has escaped the net meant to catch it.

Significance in Verification Methodology

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RELATIONSHIPS

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Genesys-x86 ← evaluates 90% 2e

Genesys-x86 was used to evaluate and discover escape bugs not found by commercial test suites.

Pentium FDIV Bug mentions → 95% 2e

The Pentium FDIV bug is cited as an example of a costly escape bug.

Pentium FIST Bug mentions → 95% 2e

The Pentium FIST bug is cited as another example of a costly escape bug.

Functional Verification Methodology for Microprocessors Using the Genesys Test-Program Generator ← evaluates 93% 2e

The paper evaluates how the methodology could have prevented known escape bugs.

Pentium Floating Point bugs ← mentions 1e

Pentium Floating Point bugs are cited as specific instances of escape bugs.

LINKED ENTITIES

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Pentium Floating Point bugs MENTIONS Extracted graph relationship

CITATIONS

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3 citations — click to collapse

[1] Escape bugs are defects in microprocessor designs that are not caught by functional verification and end up in shipped silicon, motivating rigorous verification methodologies. Functional verification methodology for microprocessors using the Genesys test-program generator. Application to the x86 microprocessors family (DATE 1999) - IBM Research

[2] A plan-driven verification methodology using an automatic pseudo-random test-program generator (Genesys) is proposed as a means of avoiding escape bugs. Functional verification methodology for microprocessors using the Genesys test-program generator. Application to the x86 microprocessors family (DATE 1999) - IBM Research

[3] The Pentium Floating Point bugs are cited as known, infamous examples of escape bugs that the proposed methodology could have helped avoid. Functional verification methodology for microprocessors using the Genesys test-program generator. Application to the x86 microprocessors family (DATE 1999) - IBM Research